From the Guidelines
CA 125 should be used to monitor treatment response and detect recurrence in women with ovarian cancer, but not as a standalone screening test for the general population due to its low specificity and potential for false positives in non-cancerous conditions. The most recent and highest quality study, published in 2023 1, supports this recommendation, highlighting the importance of combining CA 125 testing with other diagnostic tools, such as transvaginal ultrasound and CT scans, to improve the accuracy of ovarian cancer diagnosis.
Key Points
- CA 125 is a protein produced by certain cancers, particularly ovarian cancer, and can be used to monitor treatment response and detect recurrence.
- Elevated CA 125 levels can also be caused by non-cancerous conditions, such as endometriosis, pelvic inflammatory disease, and pregnancy, which limits its use as a standalone screening test.
- The test's value lies in tracking changes over time rather than single measurements, and it is typically performed before treatment begins to establish a baseline, then regularly during and after treatment to assess response.
- For high-risk women with BRCA mutations or strong family histories of ovarian cancer, CA 125 may be used as part of a surveillance strategy, usually combined with transvaginal ultrasound, though even this approach has limitations in early detection.
Diagnostic Approach
- A comprehensive diagnostic approach should include a detailed history and clinical examination, serum CA 125 testing, and imaging studies such as transvaginal ultrasound and CT scans.
- The use of multimodal screening, including serum CA 125 measurement and ultrasound imaging, may be effective in detecting ovarian cancer, but its impact on survival is still being studied 1.
- Pathological examination of tumor samples is essential for diagnosis and treatment planning, and genetic testing may be considered for therapeutic stratification.
Follow-up and Surveillance
- Follow-up and surveillance strategies should be individualized based on prognostic factors and treatment modalities, and may include regular CA 125 testing, imaging studies, and clinical examinations.
- A holistic approach to follow-up care should include patient education, monitoring and management of side effects, and assessment of psychological and social needs 1.
- The role of CA 125 testing in follow-up care is to trigger imaging and detect recurrence, rather than to screen for ovarian cancer in the general population.
From the Research
CA 125 Overview
- CA 125 is a tumor biomarker used as the primary ovarian cancer marker for the past four decades 2
- The focus on diagnosing ovarian cancer in stages I and II using CA 125 as a diagnostic biomarker has not improved patients' survival 2
- Screening average-risk asymptomatic women with CA 125 is not recommended by any professional society 2
Clinical Implications of Rising CA 125 Levels
- A progressively rising serum CA 125 level in the normal range is associated with a high likelihood of tumor recurrence in patients with epithelial ovarian cancer 3
- Three progressively rising serum CA 125 values in the normal range at 1- to 3-month intervals are associated with a high likelihood of tumor recurrence 3
- Increasing CA 125 concentration by > 5 U/ml, 3 and 6 months after treatment is associated with higher risk of relapse and lower 5-year survival rate 4
Prognostic Significance of CA 125
- Normal baseline CA 125 and normalization of this biomarker after the first cycle of chemotherapy are associated with better survival in high-risk early-stage epithelial ovarian cancer patients 5
- The pattern of CA 125 change following chemotherapy cycle 1 is associated with recurrence-free survival (RFS) and overall survival (OS) 5
- Increased concentration of CA 125 by > 5 U/ml within normal range, 3 and 6 months after treatment is an unfavorable prognostic factor in ovarian cancer patients with complete response to primary therapy 4
Surveillance Testing with CA 125
- CA 125 tests and computed tomographic (CT) scans are still routinely used for surveillance testing in patients with ovarian cancer, although their benefit has not been proven and their use may have significant implications for patients' quality of life as well as costs 6
- The use of CA 125 tests and CT scans for routine surveillance in ovarian cancer increases the use of chemotherapy and decreases patients' quality of life without improving survival 6